Linux-USB Archive on lore.kernel.org
 help / color / Atom feed
From: Johan Hovold <johan@kernel.org>
To: Manivannan Sadhasivam <mani@kernel.org>
Cc: johan@kernel.org, gregkh@linuxfoundation.org,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	patong.mxl@gmail.com, linus.walleij@linaro.org,
	mchehab+huawei@kernel.org
Subject: Re: [RESEND PATCH v4 1/3] usb: serial: Add MaxLinear/Exar USB to Serial driver
Date: Wed, 1 Jul 2020 15:09:24 +0200
Message-ID: <20200701130924.GE3334@localhost> (raw)
In-Reply-To: <20200607162350.21297-2-mani@kernel.org>

On Sun, Jun 07, 2020 at 09:53:48PM +0530, Manivannan Sadhasivam wrote:
> Add support for MaxLinear/Exar USB to Serial converters. This driver
> only supports XR21V141X series but it can be extended to other series
> from Exar as well in future.
> 
> This driver is inspired from the initial one submitted by Patong Yang:
> 
> https://patchwork.kernel.org/patch/10543261/
> 
> While the initial driver was a custom tty USB driver exposing whole
> new serial interface ttyXRUSBn, this version is completely based on USB
> serial core thus exposing the interfaces as ttyUSBn. This will avoid
> the overhead of exposing a new USB serial interface which the userspace
> tools are unaware of.
> 
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Tested-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
> ---
>  drivers/usb/serial/Kconfig     |   9 +
>  drivers/usb/serial/Makefile    |   1 +
>  drivers/usb/serial/xr_serial.c | 650 +++++++++++++++++++++++++++++++++
>  3 files changed, 660 insertions(+)
>  create mode 100644 drivers/usb/serial/xr_serial.c

> +static int xr_tiocmset_port(struct usb_serial_port *port,
> +			    unsigned int set, unsigned int clear)
> +{
> +	struct xr_port_private *port_priv = usb_get_serial_port_data(port);
> +	int ret = 0;
> +	u8 gpio_set = 0;
> +	u8 gpio_clr = 0;
> +
> +	/* Modem control pins are active low, so set & clr are swapped */
> +	if (set & TIOCM_RTS)
> +		gpio_clr |= UART_MODE_RTS;
> +	if (set & TIOCM_DTR)
> +		gpio_clr |= UART_MODE_DTR;
> +	if (clear & TIOCM_RTS)
> +		gpio_set |= UART_MODE_RTS;
> +	if (clear & TIOCM_DTR)
> +		gpio_set |= UART_MODE_DTR;
> +
> +	/* Writing '0' to gpio_{set/clr} bits has no effect, so no need to do */
> +	if (gpio_clr) {
> +		ret = xr_set_reg(port, XR21V141X_UART_REG_BLOCK,
> +				 port_priv->regs->gpio_clr, gpio_clr);
> +	}
> +
> +	if (gpio_set) {
> +		ret = xr_set_reg(port, XR21V141X_UART_REG_BLOCK,
> +				 port_priv->regs->gpio_set, gpio_set);
> +	}
> +
> +	return ret;
> +}
> +
> +static int xr_tiocmset(struct tty_struct *tty,
> +		       unsigned int set, unsigned int clear)
> +{
> +	struct usb_serial_port *port = tty->driver_data;
> +
> +	return xr_tiocmset_port(port, set, clear);
> +}

> +static void xr_dtr_rts(struct usb_serial_port *port, int on)
> +{
> +	if (on)
> +		xr_tiocmset_port(port, TIOCM_DTR | TIOCM_RTS, 0);
> +	else
> +		xr_tiocmset_port(port, 0, TIOCM_DTR | TIOCM_RTS);
> +}

By the way, don't you need to configure the DTR and RTS pins as outputs
for the serial driver as well?

According to the datasheet they are both configured as inputs by default
(or at least RTS is).

In any case, you'll need to reconfigure each pin after they are released
by gpiolib.

Johan

  parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-07 16:23 [RESEND PATCH v4 0/3] Add support for MaxLinear/Exar USB to serial converters Manivannan Sadhasivam
2020-06-07 16:23 ` [RESEND PATCH v4 1/3] usb: serial: Add MaxLinear/Exar USB to Serial driver Manivannan Sadhasivam
2020-07-01 10:34   ` Johan Hovold
2020-07-01 13:09   ` Johan Hovold [this message]
2020-06-07 16:23 ` [RESEND PATCH v4 2/3] usb: serial: xr_serial: Add gpiochip support Manivannan Sadhasivam
2020-07-01 13:02   ` Johan Hovold
2020-06-07 16:23 ` [RESEND PATCH v4 3/3] usb: cdc-acm: Ignore Exar XR21V141X when serial driver is built Manivannan Sadhasivam

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200701130924.GE3334@localhost \
    --to=johan@kernel.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=linus.walleij@linaro.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-usb@vger.kernel.org \
    --cc=mani@kernel.org \
    --cc=mchehab+huawei@kernel.org \
    --cc=patong.mxl@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-USB Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-usb/0 linux-usb/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-usb linux-usb/ https://lore.kernel.org/linux-usb \
		linux-usb@vger.kernel.org
	public-inbox-index linux-usb

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-usb


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git